Structural Regulation Of Cu-based Bimetallic Catalysts And Research On Electrochemical CO₂ Reduction Performance

The excessive use of fossil fuels has led to a significant increase in atmospheric CO₂ concentration,resulting in a series of environmental problems such as global warming,rising sea levels,and ocean acidification,which pose a threat to human survival.Therefore,the technology of capturing CO₂ from the atmosphere to produce high value-added chemicals or raw materials,while storing intermittent renewable energy,has received widespread attention.Among them,the conversion of CO₂ to high-value industrial raw materials under renewable electricity is currently one of the most promising CO₂ conversion methods to achieve carbon neutrality.It is worth noting that research has shown that converting CO₂ to CO or HCOOH is more economically feasible.However,developing highly active,selectively superior,and stable electrocatalysts remains a challenging key issue in the field of electrocatalytic CO₂reduction.This paper focuses on Cu-M bimetallic catalysts and modifies the catalysts by adjusting their composition,controlling their morphology,and doping them with non-metallic elements,in order to improve their electrocatalytic performance in CO₂reduction reaction（CO₂RR）.The main research work is as follows:1.Adjustable Cu Bi/C catalyst for controlling CO₂RR selectivity:We assembled Cu Bi/C catalysts with different compositions using a one-step reduction method with Na BH₄ as a reducing agent,to investigate the effect of Cu/Bi ratio on CO₂RR selectivity.The experimental results showed that when Cu/Bi=0.5,the Cu_0.5Bi/C electrocatalyst exhibited high selectivity for HCOOH,with a Faradaic efficiency of 95%(FE_HCOOH=95%)at-0.9 V vs.RHE and maintained high selectivity for HCOOH within a broad potential window of 400 m V（FE>90%）.It was found that the excellent catalytic activity of the Cu_0.5Bi/C catalyst was mainly attributed to the controllable regulation of the metal components,which changed the geometric environment and local electronic structure of the catalyst.In addition,the large active surface area and abundance of active sites on the catalyst surface,as well as the synergistic effect between Cu and Bi,collectively contributed to the enhancement of CO₂RR selectivity.2.Morphology-controlled Cu Sn bimetallic catalyst for enhanced CO₂ reduction to formic acid:We prepared branched Cu Sn bimetallic catalysts by constant current electrodeposition and investigated the effect of morphology on CO₂RR selectivity.The CO₂RR performance test showed that the Cu Sn catalyst prepared after 5 seconds of constant current electrodeposition exhibited high selectivity towards formic acid(FE_HCOOH=91%)at-1.4 V vs.RHE,demonstrating superior selectivity compared to other products prepared with different deposition times.During the electrocatalytic CO₂RR process,the dendritic electrocatalysts possess fine branches and exposed small surfaces.By changing the deposition time,the branching degree in the dendritic microstructure can be controlled.In addition,compared to smooth surfaces,the edges（branches）of the electrodeposited catalyst are more effective catalytic sites,and the branched catalyst enhances the activity of CO₂RR.3.B-doping to modulate the electronic structure of Cu In nanocomposite for broad potential window electrocatalytic CO₂ reduction:We developed a B-doped Cu In alloy catalyst with tunable electronic structures for efficient electrochemical conversion of CO₂ to CO.The obtained Cu In（B）showed optimal CO Faradaic efficiency(FE_CO)of99%at-0.6 V vs.RHE,and maintained high FE_CO（>90%）over a wide cathodic electrochemical window（400 m V）.Density functional theory calculations indicated that the enhancement of CO₂RR performance was mainly attributed to the electron capturing ability of high-valent B atoms,which optimized the local electronic structure of adjacent metal active sites and adjusted the binding energy between the catalyst and intermediates.This work provides a new strategy for designing electrocatalysts with tunable electronic structures for CO₂RR.